Combined effects of vibration and noise on palmar sweating in healthy subjects.

The combined effects of vibration and noise on palmar sweating were studied experimentally in healthy subjects. Ten subjects were exposed to vibration at an acceleration of 100 m.sec-2 root mean square at a frequency of 125 Hz, a noise level of 105 dB(A) at a frequency of 1000 Hz and both stimuli together. Vibration was applied to the right hand and noise to both ears from headphones. Palmar sweating was measured by the ventilated capsule method. Vibration caused a marked increase in palmar sweating of the right hand directly exposed to vibration and also of the left hand not exposed to vibration. Simultaneous vibration and noise caused a greater increase in palmar sweating than by each of the factors separately. The combined effects tended to be greater in subjects who were more susceptible to vibration or noise.